The present invention relates to a method and apparatus for testing a fluidically operated system wherein pressurized fluid is transmitted through conduits and associated valve means to actuate at least one fluid responsive mechanism. More particularly, the present invention concerns a method of testing the operation of the valving in a vehicle anti-skid brake system, without interrupting the hydraulic brake lines.
The use of anti-skid brake systems in vehicles is becoming increasing popular. Under adverse braking conditions, an anti-skid braking system not only improves the braking ability, but also improves the steerability of the vehicle. Typically, an anti-skid braking system includes a central electronic control unit connected to one or more wheel speed sensors for monitoring the wheel speed. The central control unit is connected to operate one or more electrically-actuated valves in the hydraulic braking circuit. Upon sensing an incipient wheel lock-up condition during braking, the control unit operates the valves to control the application of pressurized brake fluid to the selected wheel brakes to correct or prevent a wheel lock-up condition.
With the increasing popularity of anti-skid braking systems, there is a need for suitable diagnostic and trouble shooting equipment. For example, although an electrical connection between the central control unit and a given valve can be monitored to check whether the central control unit is sending the proper control signal to the proper valve, the transmission of such a control signal does not necessarily indicate that the mechanical components of the valve are operating properly.